Application Of SWMM Model To Rainfall Runoff Non-point Source Pollution In Urban Small Watershed

The process of urbanization and industrialization in China continues to accelerate.Urban water pollution has become a very serious environmental problem,and urban rainfall runoff non-point source pollution is one of the most important reasons.Rainfall washes away pollutants from the atmosphere and reaches the ground and washes away pollutants from the ground.Pollutants dissolve in runoff and discharge into lakes,rivers with the runoff process,resulting in more serious pollution of urban waters.This paper takes Wuhan Yujia Lake Watershed as the research object,constructing the Yujia Lake watershed rainfall runoff non-point source pollution model.Through the model simulation of the quantitative research and prediction of city rainfall runoff non-point source pollution,some ideas and methods for controlling and managing city rainfall runoff non-point source pollution are proposed.The main research contents are as follows:(1)The simulation mechanism of SWMM model is analyzed from 3 aspects,which are surface rainfall runoff calculation,land use pollution buildup and washoff,transport system simuation calculation.It provides a theoretical basis for the construction of rainfall runoff source pollution model.(2)On the basis of research group project,the basic data of non-point source pollution of rainfall runoff are obtained,and then the model is constructed.Establishing model is divided into surface generalization and setting model parameters.The Yujia Lake watershed is generalized to the 31 subcatchments,35 joints and 30 pipe canals and 5 water outlets,14 and 16 parameters are respectively arranged in the hydrological and hydraulic module and water quality module.(3)The sensitivity analysis of parameters is based on the modified Morris classification screening method.The calibration of all parameters is according to the measured data of rainfall,then the model is verified and measured values the average error is within 20%,with good reliability.(4)Using the rainfall process under different return periods as rainfall input,different rainfall intensity was simulated to study the water quality and water quality dynamic change of rainfall runoff non-point source pollution and was used to test the effect of the constructed model in the prediction and analysis of the urban rainfall runoff non-point source pollution,to prove the reliability of the model and to play an important role in urban non-point source pollution control management.